System and method for detection of mobile operating through a repeater

ABSTRACT

A system and method for a network analysis system operating in a wireless communication system with repeaters is disclosed. Embodiments of the system and method enable the network analysis system to determine if signals being received by the network receivers arrive directly from a target mobile appliance or if the signals are passing through a repeater. The repeaters through an augmentation measure attribute of a received signal to a network manager and based on these attributes it is determine whether the signal is served by a repeater or other network device.

CROSS REFERENCES

This non-provisional Application claims priority benefit of co-pendingProvisional Patent Application Ser. No. 60/570,067, titled SYSTEM ANDMETHOD FOR DETECTING A MOBILE STATION OPERATING THROUGH A REPEATER,filed May 12, 2004, the contents of which are herein incorporated byreference.

This non-provisional Application claims priority benefit of co-pendingProvisional Patent Application Ser. No. 60/570,081, titled SYSTEM ANDMETHOD FOR IDENTIFYING THE PATH OR DEVICE ON THE PATH OF A COMMUNICATIONSIGNAL USING (1+r(t)) AMPLITUDE MODULATION, filed May 12, 2004, thecontents of which are herein incorporated by reference.

The present non-provisional application claims priority benefit ofco-pending provisional application Ser. No. 60/570,082, titled SYSTEMAND METHOD FOR IDENTIFYING THE PATH OR DEVICES ON THE PATH OF ACOMMUNICATION SIGNAL filed May 12, 2004, the entirety of which is herebyincorporated by reference.

BACKGROUND

Applicant's disclosure is directed generally towards a wirelesscommunications network for determining whether a signal from a mobileappliance is operated on by a repeater or other network device.

The use of wireless communication devices such as telephones, pagers,personal digital assistants, laptop computers, etc., hereinafterreferred to collectively as “mobile appliances,” has become prevalent intoday's society.

FIG. 1 shows a conventional mobile-appliance communication system havingbase stations 10 a-c for communicating with a mobile appliance 20. Eachbase station 10 contains signal processing equipment and an antenna fortransmitting to and receiving signals from the mobile appliance 20 aswell as other base stations. A Base Station Controller (“BSC”) and/orMobile Switching Center (“MSC”) 45 typically is connected to each basestation 10 through a wire line connection 41.

To meet the ever growing demand for mobile communication, wirelesscommunication systems deploy repeater stations to expand range andconcentration of coverage. In FIG. 1, a repeater 50 a, associated withbase station 10 a, is located to extend the coverage area to encompassthe back side of the mountain 1. The repeater 50 b, associated with basestation 10 c, is mounted on a building and is used to provide servicewithin the building 2.

Repeaters typically fall into two categories: (1) non-translating, alsoknown as wideband, and (2) translating, also known as narrowband. Asshown in FIG. 2 a, a non-translating repeater 250 simply passes theforward F_(f1) and reverse R_(f1) frequencies from the base station 210and mobile appliance 220 respectively to and from the repeater coveragelocation. Often wideband repeaters are “in-building” or serve limitedcoverage areas. While the description of non-translating repeaters aboveand translating repeaters below are described in reference to frequency,their operation can equally be described in terms of channels, and theuse of the term frequency should not be construed to limit the scope ofthe present disclosed subject matter.

A translating repeater assigns the mobile to a different traffic channelunbeknownst to the base station, mobile switch, MPC, and the basestation controller. As shown in FIG. 2 b, the translating repeater usesthe base station traffic channel R_(f1) for repeater 250 to base station210 communication while the mobile appliance 220 utilizes a separatefrequency R_(f2) for mobile to repeater communications. Translatingrepeaters act similarly in the forward direction using F_(f1) from thebase station 210 to the repeater station 250 and F_(f2) from therepeater station 250 to the mobile appliance 220. In both cases, theexistence of the repeater is usually transparent to the network.

The function of the repeater station can be assumed to be equivalent toconverting all signals in some received bandwidth from a Radio Frequency(RF) to some Intermediate Frequency (IF). The IF signal bandwidth isthen up-converted by suitably frequency shifting this bandwidth whileconcurrently applying both amplification and a fixed delay to thesignals.

For example, let the set of signals transmitted by N mobiles in therepeaters' input bandwidth be denoted by

${{S(t)} = {\sum\limits_{k = 1}^{N}{{a(k)}{x\left( {k,t} \right)}{\sin({wt})}}}},$where the signal from a given mobile is denoted by x(k, t). The signalx(k, t) is contained in the repeater bandwidth and w is the angularfrequency center of the RF bandwidth. The repeater downshifts theaggregate signal to generate

${{D(t)} = {\sum\limits_{k = 1}^{N}{{a(k)}{x\left( {k,t} \right)}{\sin({vt})}}}},$in which v is now representative of the center of the IF bandwidth. Theentire signal D(t) is now converted back to RF by operations that areequivalent to forming the signal

${{R\left( {t + T} \right)} = {{G{\sum\limits_{k = 1}^{N}{{a(k)}{x\left( {k,t} \right)}{\sin({vt})}{\cos\left( {{wt} - {vt}} \right)}}}} + {G{\sum\limits_{k = 1}^{N}{{a(k)}{x\left( {k,t} \right)}{\cos({vt})}{\sin\left( {{wt} - {vt}} \right)}}}}}},$in which G is the repeater gain. The last equation can be written in amore convenient, mathematical manner by noting that R(t) can be derivedfrom D(t) by writing it as R(t+T)=Re{G exp(j(w−v)tI(t))}, where Gexp(j(w−v)t) is the complex representation of the multiplicative signalintroduced by the repeater on the downshifted signal bandwidth and I(t)is the complex representation of D(t).

Essentially, the function of the repeater is to convert the RF signal toan IF signal, delay and amplify that IF signal, up-convert the signalback to RF, and transmit the signal. This is true for both translatingand non-translating repeaters.

Repeaters typically communicate with the host base station via an RFlink as shown in FIG. 3 between base station 310 and repeater 350 a.This connection allows remote operation of the repeater without physicalties back to the host base station, which is particularly advantageousin rugged or other areas where laying lines are difficult or costly.Some repeaters, generally non-translating repeaters, use a fiber opticor copper wire “tether” instead of an RF link to communicate with thehost base station as shown in FIG. 3, where base station 310 isconnected to repeater station 350 b by tether 351. RF signals are placedonto the tether at the repeater and then summed into the normal basestation antenna path at the antenna feed interface 311 at the host basestation. After integration into the normal base station antenna path,the signal from the repeater is indistinguishable to the base stationregarding its origin (e.g., from the base station antennas or from atether). In this tether architecture as well, the host base station hasno knowledge of the repeater's existence or that a call is being servedby the repeater.

Neither the base station nor the switch knows that a repeater or othernetwork device is serving a call. For example, a repeater installed asan in-building distribution system would use indoor antennas tocommunicate with the indoor handsets and an outdoor antenna tocommunicate with the host base station. In order to accomplish this,there is a need to overcome the deficiencies in the prior art byemploying a novel system and method that is capable of identifying whena mobile's signal is being received via a repeater or other networkdevice. In view of this need, it is an object of the disclosed subjectmatter to present a method for determining whether a signal is receiveddirectly from the mobile or from a repeater in the communicationnetwork.

The ability to discern the difference between direct signals andrepeated signals (i.e., signals that arrive via a repeater) allows forthe system to better managed and is thus advantageous.

These objects and other advantages of the disclosed subject matter willbe readily apparent to one skilled in the art to which the disclosurepertains from a perusal of the claims, the appended drawings, and thefollowing detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prior art wireless communication system.

FIG. 2 a is an illustration of the operation of a prior artnon-translating repeater station.

FIG. 2 b is an illustration of the operation of a prior art translatingrepeater station.

FIG. 3 is an illustration of a prior art wireless communication systemwith repeater stations connected with an RF link and over a tether.

FIG. 4 is a representative flow chart for the operation of a repeater inan embodiment of the present subject matter.

FIG. 5 is a representative flow chart for the operation of a networkanalysis system according to an embodiment of the present subjectmatter.

DETAILED DESCRIPTION

For the purposes of describing the present subject matter, acommunication system is the entirety of an information source (e.g., amobile transmitter), a transmitted signal conveying that information, acommunication path or link/channel, devices along the path through whichthe signal passes (e.g., a repeater), a host network and an intelligentreceiver (e.g., scanning receiver) distinct from the host network.

The current subject matter relates to a method to determine if a mobilestation operating in a wireless network utilizing a repeater iscommunicating with the base station through the repeater or othernetwork devices or directly with the base station. As previouslydiscussed, repeaters are used to “repeat” the RF signal to enhancerange, coverage or service quality; and, mobile appliances attached tothe wireless network and used as terminal devices for voice or datainterfacing.

A wireless operator may want to know how a particular mobile applianceis being served in an area to understand how his wireless network isoperating or to size and provision repeaters or other network equipmentin an area.

The present subject matter discloses an augmentation to the repeater(s)to assist the network in determining which mobile appliances areoperating through the repeater(s).

The augmentation is composed of a scanning receiver and a mechanism forinterfacing to a data service used to communicate with the manager. Theaugmentation may be housed in the repeater and may be connected to therepeater-to-mobile antenna of the repeater. Alternatively, theaugmentation may have an antenna and receiver independent of therepeater. Moreover, the augmentation may be physically and operablyindependent of the repeater altogether. The augmentation scans thereverse link channels where a mobile appliance might transmit andmeasures energy and/or signal characteristics. These channels can berepresented as RF frequencies, time slots, spreading codes or anycombination thereof. These measurements may be used to determine if amobile appliance is operating in the proximity of the repeater antenna.If signal strength and/or quality are high (or within a certain band),then it may be assumed that the mobile is operating through therepeater.

The measurements and/or channel indicators for a mobile appliancedetermined to be operating through the repeater are transmitted to themanager. The measurements may be analyzed at the augmentation or at themanager to arrive at such a determination. The measurements can beanalyzed based on signal strength, particular band of received power, orsignal characteristics. The band of received power may be mapped to thepower management algorithms that a particular air interface will employto control the power level of a mobile appliance. Decoding of certainsignal characteristics (i.e., presence of sync codes) may indicatesufficient power level to measure signal characteristics, and providepositive indication that the signal energy on that channel is from adevice connected to the wireless network of interest.

The measurements or analyses are sent over an interface from theaugmentation to the manager over a data service. The data service ismost conveniently a data transport mechanism supported by the wirelessnetwork of interest. For example, in a Global System for MobileCommunication (GSM) network that supports General Packet Radio Service(GPRS), the measurement data from the augmentation or channel resultscould be transferred to the manager using this data service. ShortMessage Service (SMS) services available in TDMA and GSM are alsocandidates. Wireless connections (e.g., T1, modem, frame relay) are alsoan option. The manager serves as the control and management device forthe augmentation(s), and as an interface point for access to the list ofmobile appliances operating through certain repeaters. The manager canhave data files indicating where repeaters with augmentations arelocated in the network, and through connections to other wirelessnetwork entities, translate channel information to mobile identityinformation. In a GSM network, this might consist of translating atraffic channel assignment to a Temporary Mobile Station Identifier(TMSI) or Mobile Station International ISDN Number (MSISDN) throughaccess to network data at the Base Station Controller (BSC) or HLR/VLR.

Implementation of the augmentation and manager in the described fashionis convenient and cost effective. The functions incorporated into theaugmentation are formed from common building blocks found in commercialhandsets. Thus, the augmentation may be added to a repeater for afraction of the recurring cost of handset components. The manager may beconceived as a new software component executing on an existing computingdevice in a wireless network, shared with other functions associatedwith network entities to which it would be easy to interface.

An important aspect of the presently disclosed subject matter is thatthe communication network can determine when a received signal from amobile has passed through a repeater or other network devices. Prior artsystems do not have this capability and consequently treat all thereceived signals as having been directly received from the targetmobile. The foregoing embodiments are exemplary only and shall not beused to limit the invention. These examples and others are discussed inmore detail below.

FIG. 4 is a representation of a network analysis system within acommunication system according to an embodiment of the presentdisclosure. The communication system includes a repeater 401, a basestation 404, and a base station controller 402, as well as a pluralityof mobiles, 420 and 405. As illustrated, the mobile 420 communicatesdirectly with the base station 404, and the mobile 405 communicates withthe base station 404 through the repeater 401. Antennas 408 and 407 areassociated with the base station 404 and the repeater 401, respectively.The repeater 401 is augmented with a scanning receiver that communicateswith a manager over an interface 450. The interface 450 may take theform of a separate channel within the communication system or adedicated wireless, wireline or other communication link.

FIG. 5 is a representational flow chart of a method for detecting amobile operating through a repeater according to an embodiment of thepresent subject matter. The mobile 501 transmits an information signal.The repeater 510, in normal operation, receives, amplifies andretransmits the signal as shown in Block 511. The scanning receiver 515associated with the repeater scans for transmitted signals; and, uponacquiring the transmitted signal, either from the repeater or anindependent antenna, the scanning receiver measures attributes of thesignal as shown in Block 517. In Block 518, the scanning receiver 515 oraugmentation sends the measurement of the attribute of the signal to themanager 530 over a communication interface 550. Alternatively, ananalysis of the measured attributes can be conducted at the augmentationand the results of the analysis may be forwarded to the manager 530. Thebase station 520 receives the signal in Block 521 and operates in anormal fashion, with the operation of the augmentation 515 and manager530 being transparent to the base station. The manager 530, uponreceiving the measured attributes or analyses, determines if themobile's signal is likely operated upon by the repeater 510. Thisdetermination is preferably based on proximity of the mobile to therepeater. For example, if the augmentation 515 measures a high transmitpower level, as related to a threshold as in the case of mobile 405,then it is likely that mobile 405 is served by the repeater 510.However, if the transmit power level is below a predetermined level orthreshold, as is likely for mobile 420, then it is not likely the mobile420 is served by the repeater 510. The measured attributes may includesignal strength, signal to noise ratio (SNR), band of received power, orother signal characteristics. In addition to communication of themeasured attributes, the augmentation 515 also preferentially sends achannel or other identifier relating the measured attributes to thesignal measured.

While preferred embodiments of the present inventive system and methodhave been described, it is to be understood that the embodimentsdescribed are illustrative only and that the scope of the embodiments ofthe present inventive system and method is to be defined solely by theappended claims when accorded a full range of equivalence, manyvariations and modifications naturally occurring to those of skill inthe art from a perusal hereof.

1. A wireless communication system comprising: a plurality of basestations; at least one mobile appliance; at least one repeater; and acontrol and management device, wherein the at least one repeater furthercomprises a scanning receiver, and an interface wherein the scanningreceiver is adapted to measure attributes of reverse link channels todetermine whether a signal has been served by the at least one repeateror has been received directly from a mobile appliance and wherein theinterface operably connects the at least one repeater and the controland management device, wherein the attributes are selected from thegroup of signal characteristics, signal strength, and band of receivedpower.
 2. The wireless communication system of claim 1, wherein thescanning receiver is connected to an antenna of the at least onerepeater.
 3. The wireless communication system of claim 1, wherein theat least one repeater and control and management device are connectedvia a wireless channel of one of the plurality of base stations.
 4. Thewireless communication system of claim 1, wherein the control andmanagement device is connected to mobile switching center.
 5. A methodof determining if a signal, from a source transmitter, received at areceiver has passed through a network device comprising: scanningsignals at the network device; measuring an attribute of the scannedsignals; communicating to a system manager the attributes of the scannedsignals measured at the network device; and, determining which signalsare served by the network device or are received directly from a mobileappliance based at least in part of the measured attributes, wherein theattributes reflect a proximity to the network device, and wherein theattributes are from the group of signal strength, signalcharacteristics, and band of received power.
 6. The method of claim 5,wherein the network device is a repeater.
 7. The method of claim 5,wherein the network device is a micro station.
 8. The method of claim 5,wherein identifiers of the reverse channel are communicated along withthe attributes.
 9. The method of claim 8, wherein the identifiers of thereverse channel are translated into mobile appliance identityinformation with information provided from a mobile switching center.10. The method of claim 5, wherein the attributes are communicated tothe system manager via the receiver.
 11. The method of claim 5, whereinthe attributes are compared to a threshold at the system manager.
 12. Amethod of determining if a mobile appliances signal received at a basestation has been operated on by one or more repeaters comprising:scanning reverse channel signals at the one or more repeaters; measuringone or more attributes of the scanned reverse channel signals;transmitting to a system manager over a link the attributes of thescanned reverse channel signals and channel information of the reversechannel signals; determining the proximity of the mobile appliance tothe one or more repeaters based at least in part by the measuredattributes; and determining which reverse channel signals are served bythe one or more repeaters based at least in part by the proximity of themobile appliance to the one or more repeaters.
 13. The method of claim12, wherein the attributes comprise the group of signal strength, bandof received power and signal characteristics.
 14. The method of claim12, wherein the link is a wireless communication channel.
 15. The methodof claim 12, wherein the link is a wireline.
 16. The method of claim 12,wherein the attributes are compared to thresholds at the system manager.17. The method of claim 12, wherein the channel information istranslated into mobile appliance identity information with informationprovided from a mobile switching center.